Cerulean Studios' Trillian has long been one of the top multiprotocol IM clients. The program offers simultaneous access to the fab-five chat clients: Yahoo Messenger, MSN Messenger, ICQ, IRC, and AIM, but still doesn't support Jabber/Google Talk in the basic version. For that, users will have to upgrade to Trillian Pro.
Despite lacking this major chat protocol, Trillian's interface is slick and sharp, a professional design that's way ahead of its competitors. Users can import passwords, buddy lists, and client preferences, as well as transfer files and encrypt chats. SMS text messaging and audio chat are supported in the basic version, with video support restricted to the pro edition. Trillian's skin support has improved in more recent versions, as has AIM stability. So if you need help managing your schizophrenic chatting identity, don't go all Sybil on your friends--just get Trillian.